Unraveling the mysteries of exotic superconductors

Scientists at the US Department of Energy's Ames Laboratory are using specialized techniques to help unravel the mysteries of iron-based superconductors. As part of an international collaboration, (from left) Kiyul Cho, Ruslan Prozorov and Makariy Tanatar found that magnetism may be helping or even responsible for superconductivity in iron-based superconductors. Credit: Ames Laboratory -- USDOE

In traditional electrical lines, a significant amount of energy is lost while the energy travels from its source to homes and businesses due to resistance. Superconductors, materials that when cooled have zero electric resistance, have the promise of someday increasing the efficiency of power distribution, but more must still be learned about superconductors before they can be widely used for that purpose.

Scientists at the U.S. Department of Energy's Ames Laboratory are using specialized techniques to help unravel the mysteries of a new type superconductor that was discovered in 2008. Ames Lab physicists were part of an international collaboration that also included scientists at Kyoto University in Japan, University of Illinois at Urbana-Champaign and University of Bristol in the United Kingdom to study the materials.

The group found that magnetism may be helping or even responsible for superconductivity in iron-based superconductors. The results were published in the June 22 issue of Science.

"The first step in designing superconductors for new technologies that will help save energy is better understanding of how superconductors work," says Ruslan Prozorov, who led the team at Ames Lab that also included Kiyul Cho and Makariy Tanatar.

Unfortunately, most conventional measurements of material parameters, such as resistivity, aren't useful in the state of superconductivity. But Prozorov several years ago helped developed a technique to measure how far the magnetic field penetrates into a superconductor. This length is called the London penetration depth, and it reveals basic information about a material, even in the superconducting state.

"London penetration depth is one of the few quantities we can measure in a superconducting state to learn more about what's going on, so the technique we specialize in here at Ames Laboratory was particularly useful for this research project," said Prozorov, who is also an associate professor of physics and astronomy at Iowa State University. "In this collaboration, we studied a barium-iron-arsenic-phosphorus material at near zero Kelvin, and our London penetration depth measurements suggested that magnetism is responsible for superconductivity in iron-based superconductors. Typically, magnetism is detrimental to superconductivity, but when it is weakened enough, it might actually be helping."

The international team's research helps answer one of the central questions about how iron-based superconductors work.

"Iron-based superconductors may open the door to new energy technologies," said Prozorov. "But we'll only get there through materials science and understanding the mechanism of superconductivity in these new iron-based materials."

Related Stories

Physicists at the U.S. Department of Energy's Ames Laboratory have experimentally demonstrated that the superconductivity mechanism in the recently-discovered iron-arsenide superconductors is unique compared to all other ...

(PhysOrg.com) -- Scientists from Queen Mary, University of London and the University of Fribourg (Switzerland) have found evidence that magnetism is involved in the mechanism behind high temperature superconductivity.

Superconductivity appears to rely on very different mechanisms in two varieties of iron-based superconductors. The insight comes from research groups that are making bold statements about the correct description of superconductivity ...

(PhysOrg.com) -- Scientists at U.S. Department of Energy's Argonne National Laboratory used inelastic neutron scattering to show that superconductivity in a new family of iron arsenide superconductors cannot be explained ...

New images of iron-based superconductors are providing telltale clues to the origin of superconductivity in a class of ceramic materials known as pnictides. The images reveal that electrons responsible for the superconducting ...

Recommended for you

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers"—very low frequency packets of radio waves that race along magnetic field lines. This first-of-its-kind ...

Mixing liquids is easy, or at least scientifically understood: a drop of food coloring will eventually mix into a cup of water through diffusion, and a dollop of cream can be mixed into coffee with a spoon through what is ...

A new type of pressure sensor based on light could allow the creation of sensitive artificial skins to give robots a better sense of touch, wearable blood-pressure monitors for humans and optically transparent touch screens ...

A kiwi physicist has discovered the energy difference between two quantum states in the helium atom with unprecedented accuracy, a ground-breaking discovery that contributes to our understanding of the universe and space-time ...

A team of researchers from the U.S. Naval Research Laboratory and Washington University has learned more about possible ways to store modern nuclear waste by studying an ancient natural fission reactor. In their paper published ...

3 comments

This article is interesting but the presentation is short on details. In addition to the June 2012 article available as reported above, there is an article published 22 September 2011 by Prozorov and Kogan available publicly on the web entitled "London Penetration Depth in Iron-Based Superconductors." Plenty of info available there. Cho and Tanatar were also on that team.

This is good research, and it seems consistent with other research on pnictide superconductivity, to the effect that magnetism is "responsible for superconductivity" (or at least helpful)in the pnictides. (The why? part remains unclear.) I think the second part of the statement deserves some discussion: "...when [magnetism] is weakened enough, it might actually be helping."

I see it a little differently. At low temperatures, everything else is subdued or suppressed as well. So the "weakened" magnetism might be relatively more influential than the forces that prevailed in the self-organization of the material at points above the transition temperature. Greater relative strength and range of influence might be the key details, not the diminished absolute strength of the magnetic force per se.

The fact that superconductivity arises in iron based materials implies, as a matter of common sense, that magnetism must be beneficial as to pnictide superconductivity.

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.